If salivary amylase is lacking in saliva, the event that will be affected is (b) Starch breaking down into sugars.
Explanation: Salivary amylase is an enzyme specifically designed to break down starch into simpler sugars like maltose, so its absence will directly impede this process.
Why other options are incorrect:
(a) Proteins breaking down into amino acids:
This process is primarily facilitated by proteases, enzymes not found in significant amounts in saliva. While some protein digestion might start in the mouth due to the presence of peptidases, it is not the main function of salivary amylase.
(c) Fats breaking down into fatty acids and glycerol:
This is the function of lipases, not amylase. Although saliva does contain a small amount of lipase called lingual lipase, its primary role is not fat breakdown but rather the breakdown of lipids in taste perception.
(d) Absorption of vitamins:
Absorption of vitamins primarily occurs in the small intestine, not the mouth. While saliva plays a role in dissolving and transporting food particles, vitamin absorption is a later stage in the digestive process.